Dell HHB Owner's Manual page 128

NOTE: If the blade is turned off for long periods of time (for weeks or months), the NVRAM may lose its system
configuration information. This situation is caused by a defective battery.
NOTE: Some software may cause the blade's time to speed up or slow down. If the blade operates normally except
for the time maintained by the System Setup, the problem may be caused by a software rather than by a defective
battery.
Related tasks
Removing the blade
Installing a blade
Replacing the NVRAM backup battery
Related reference
Getting help
128 Troubleshooting your system